A. You are describing a fascinating occurrence called the "warm-up phenomenon" that has puzzled doctors for decades. In the clinic, it can be demonstrated by having a patient do two exercise tests, one right after the other. Many people with problems in the blood vessels nourishing the heart will be able to exercise longer and with less or no chest pain (angina) on the second exercise test. Several physiological mechanisms have been proposed for this, but no explanation has emerged.
The best message for people with coronary artery disease is to do just what you're doing: Warm up before exercising so you can get in a good long walk at a moderate pace. This allows you to reap the many benefits of exercise without having to deal with chest pain.
If your episodes of angina are affecting your daily life and you haven't talked with your doctor about it, I urge you to do so. It may be possible to adjust your medications to prevent many of the episodes. Angioplasty or bypass surgery may also be an option if angina is getting in the way of an active life. Although these procedures generally don't prolong life, they are very effective at reducing angina. -- Richard Lee, M.D., Associate Editor, Harvard Heart Letter